1. Field of the Invention
The present invention relates to an apparatus and method for controlling a fan drive in various computer systems such as a notebook computer, a personal computer and etc
2. Background of the Related Art
FIG. 1 is a block diagram illustrating the configuration of a conventional computer system. Various computer systems such as a notebook computer, a personal computer and etc. include a central processing unit (CPU) 10, a video controller 11, a north bridge 12, a random access memory (RAM) 13, a hard disk drive (HDD) 14, a south bridge 15, a thermal sensor 16, a microcomputer 17, a cooling fan module 18, etc.
Further, the south bridge 15 is equipped with a power manager (PM) 150 for managing system power. The microcomputer 17 is equipped with a pulse width modulation (PWM) control signal generator 170 for variably controlling a rotation speed of a cooling fan.
The thermal sensor 16 detects an internal temperature of a computer varying with heat from, for example, the CPU 10, the HDD 14 or etc., and outputs a signal indicating the detected temperature to the PM 150 located within the south bridge 15. The PWM control signal generator 170 located within the microcomputer 17 generates a PWM control signal adapted to the detected temperature and outputs the generated PWM control signal to the cooling fan module 18.
In response to the PWM control signal, the cooling fan module 18 performs an operation for incrementing or decrementing the rotation speed of a cooling fan through a plurality of stepped speeds. As shown in FIG. 2, the cooling fan module 18 includes a motor drive 180, a motor 181 and a cooling fan 182.
The motor drive 180 applies, to the motor 181, a drive voltage corresponding to the PWM control signal outputted from the PWM control signal generator 170 so that the cooling fan 182 can be rotated at a predetermined rotation speed in response to the drive voltage. The PWM control signal generator 170 generates a PWM control signal for rotating the cooling fan 182 at a high speed where the internal temperature detected by the thermal sensor 16 is relatively high. On the other hand, the PWM control signal generator 170 generates a PWM control signal for rotating the cooling fan 182 at a low speed where the internal temperature detected by the thermal sensor 16 is relatively low.
The PWM control signal generator 170 can use, for example, hardware based upon 4-bit resolution as shown in FIG. 3. In this case, 16 PWM control signals (PWM PATTERNS 0˜15) are present so that the rotation speed of the cooling fan 182 can vary by 16 STEPS (0˜15).
Further, where the minimum and maximum rotation speeds of the cooling fan 182 are set to “0” RPM (Revolutions Per Minute) and “4500” RPM, respectively, a rotation speed difference of the cooling fan 182 between consecutive steps becomes “300” RPM. Assuming that the optimum rotation speed of the cooling fan 182 necessary for reducing the internal temperature of the computer is “3500” RPM, the PWM control signal generator 170 outputs a PWM control signal PWM PATTERN 12 corresponding to “3600” RPM, which is the PWM pattern closest to “3500” RPM.
As described above, the related art computer system and method have various disadvantages. For example, the cooling fan 182 was rotated at “3600” RPM according to the PWM control signal PWM PATTERN 12 because it was the closest to “3500” RPM of the PWM patterns shown in FIG. 3. In this case, the cooling fan 182 is unnecessarily rotated by an additional “100” RPM, and hence power is wasted. In the case of the notebook computer, a battery available time is reduced because of the unnecessary rotation. Further, as the cooling fan 182 is unnecessarily rotated, noise can be incurred.
To address the above problems, the PWM control signal generator 170 can use hardware based upon a higher predetermined bit resolution, for example, hardware based upon 8-bit resolution. However, the hardware based upon the 8-bit resolution is more expensive to install, control and manage than that based upon the 4-bit resolution. Where the hardware based upon the 8-bit resolution is used, there are problems in that a size of the hardware is increased and that it is difficult for the computer system to be simplified.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.